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-a²-4b²+4ab=?(分解因式,

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-a²-4b²+4ab=?(分解因式,
1.-a²-4b²+4ab=?
2.(x-y)²-10(x-y)+25=?
3.(x²-1)²+6(1-x²)+9=?
4.4(x+y)²-20(x+y)+25=?
5.1/4x²+x+1=?
6.(3x-5y)²+2(3x-5y)+1=?
7.4(2x-y)²+24(2x-y)+36=?
8.(2x-5)²+28x-21=?
(分解因式,
-a²-4b²+4ab=?(分解因式,
1.-a²-4b²+4ab
=-(a^2-4ab+4b^2)
=-(a-2b)^2
2.(x-y)²-10(x-y)+25
=(x-y)^2-2*5(x-y)+5^2
=(x-y-5)^2
3.(x²-1)²+6(1-x²)+9
=(x^2-1)^2-2*3(x^2-1)+3^2
=(x^-1-3)^2
=(x^2-4)^2
=(x+2)^2(x-2)^2
4.4(x+y)²-20(x+y)+25
=[2(x+y)]^2-2*[2(x+y)]*5+5^2
=[2(x+y)-5]^2
=(2x+2y+5)^2
5.1/4x²+x+1
=(x^2+4x+4)/4
=(x+2)^2/2^2
=(x/2+1)^2
6.(3x-5y)²+2(3x-5y)+1
=(3x-5y+1)^2
7.4(2x-y)²+24(2x-y)+36
=[2(2x-y)]^2+2*[2(2x-y)]*6+6^2
=[2(2x-y)+6]^2
=4(2x-y+3)^2
8.(2x-5)²+28x-21
=4x^2-20x+25+28x-21
=4x^2+8x+4
=4(x^2+2x+1)
=4(x+1)^2